Post Office addresses sometimes diverge from the addresses given by city or county zoning. This is why there is sometimes both a physical address and a mailing address for a place. Often they are the same, but this seems to be one of those cases where they are not. Also, if a large building that processes its own mail, as seems to be the case here, spans multiple city zoned lots, it often just uses one of them for its address, but that doesn't mean the others still don't exist, and the city does have addresses for them.
Since navigation systems typically go by physical city lot addresses, being that they are used to find a physical place, rather than to mail someone a letter, Waze will likely route to the spot where the building's mailing address reflects the actual city lot, which sometimes unfortunately isn't the entrance to the building.
If you frequently visit a place like this, it's best to just pull up at the front of the building or where you'd normally park and use your current location to find out what the city lot address there is and store that as a favorite to use as your destination. That's what I have to do with several places here in New Jersey where the post office and local town can't seem to agree on addresses. But beyond that, I think that these kinds of discrepancies are unfortunately beyond the scope navigation systems like Waze.